A senior US official said Wednesday he was hopeful after he held the highest-level talks with Myanmar in nearly a decade but warned the military regime must do more to prove its openness, AFP reported.

Kurt Campbell, the assistant secretary of state for Asian affairs, met Tuesday with a delegation from Myanmar in New York one day after he unveiled a new blueprint of engaging the longtime pariah state.

"There were certainly no breakthroughs, but a very clear determination that dialogue was possible on the side of Burma," Campbell, using Myanmar's old name, said as he testified before the Senate Foreign Relations Committee.

He said that the US side had "intensively" prepared for the meeting and clearly laid out its goals for the regime, including an improvement in human rights.

The United States wants the regime to free political prisoners, particularly democracy icon Aung San Suu Kyi, and to initiate a dialogue with restive ethnic groups.

Campbell warned Myanmar not to repeat the example of a referendum last year. To international doubts, the junta said more than 92 percent of voters approved a military-backed constitution in a vote held shortly after a major cyclone.

"We think much more dialogue and discussion inside the country is an essential first step and even then it's not clear where we will end up," he said.

He said he told the delegation from Myanmar that "such a dialogue was of critical importance and if it were implemented like the referendum that in fact it would get virtually no international support or recognition."

State Department spokesman Philip Crowley said Campbell and his deputy Scot Marciel also raised US concerns about Myanmar's "relationship with North Korea" as well as "our proliferation concerns associated with that."

During a visit to Thailand in July, US Secretary of State Hillary Clinton said the communist state could be sharing atomic technology with military-ruled Myanmar, posing a major threat to the region.

President Barack Obama's administration has made dialogue a signature policy, saying it is open to talks with staunch US foes such as Iran and Cuba.

The State Department said Campbell's meetings Tuesday were the highest-level interaction between the administration and the junta since September 2000 under the Bill Clinton administration.

Crowley, the assistant secretary for public affairs, described the two-hour encounter Tuesday in the Waldorf Astoria hotel as "a cautious beginning and an initial meeting." He added that "time and patience" will be required as both sides pursue further talks.